EP2227807A1 - Method of recording content on disc, method of providing title key, apparatus for recording content on disc, and content providing server - Google Patents

Method of recording content on disc, method of providing title key, apparatus for recording content on disc, and content providing server

Info

Publication number
EP2227807A1
EP2227807A1 EP08793541A EP08793541A EP2227807A1 EP 2227807 A1 EP2227807 A1 EP 2227807A1 EP 08793541 A EP08793541 A EP 08793541A EP 08793541 A EP08793541 A EP 08793541A EP 2227807 A1 EP2227807 A1 EP 2227807A1
Authority
EP
European Patent Office
Prior art keywords
key
disc
content
encrypted
server
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08793541A
Other languages
German (de)
French (fr)
Other versions
EP2227807A4 (en
Inventor
Dae-Jong Lee
Kil-Soo Jung
Sung-Ryeul Rhyu
Man-Seok Kang
Joon-Hwan Kwon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Samsung Electronics Co Ltd
Original Assignee
Samsung Electronics Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Samsung Electronics Co Ltd filed Critical Samsung Electronics Co Ltd
Publication of EP2227807A1 publication Critical patent/EP2227807A1/en
Publication of EP2227807A4 publication Critical patent/EP2227807A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F15/00—Digital computers in general; Data processing equipment in general
    • G06F15/16—Combinations of two or more digital computers each having at least an arithmetic unit, a program unit and a register, e.g. for a simultaneous processing of several programs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/0021—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/0021—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier
    • G11B20/00217—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier the cryptographic key used for encryption and/or decryption of contents recorded on or reproduced from the record carrier being read from a specific source
    • G11B20/00224—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier the cryptographic key used for encryption and/or decryption of contents recorded on or reproduced from the record carrier being read from a specific source wherein the key is obtained from a remote server
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/0021—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier
    • G11B20/00217—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier the cryptographic key used for encryption and/or decryption of contents recorded on or reproduced from the record carrier being read from a specific source
    • G11B20/00246—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier the cryptographic key used for encryption and/or decryption of contents recorded on or reproduced from the record carrier being read from a specific source wherein the key is obtained from a local device, e.g. device key initially stored by the player or by the recorder
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/0021—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier
    • G11B20/0042—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier the copy protection scheme being related to a specific access protection standard
    • G11B20/00449—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier the copy protection scheme being related to a specific access protection standard content scrambling system [CSS]
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/0021—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier
    • G11B20/00485—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier characterised by a specific kind of data which is encrypted and recorded on and/or reproduced from the record carrier
    • G11B20/00492—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier characterised by a specific kind of data which is encrypted and recorded on and/or reproduced from the record carrier wherein content or user data is encrypted
    • G11B20/00528—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving encryption or decryption of contents recorded on or reproduced from a record carrier characterised by a specific kind of data which is encrypted and recorded on and/or reproduced from the record carrier wherein content or user data is encrypted wherein each title is encrypted with a separate encryption key for each title, e.g. title key for movie, song or data file
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/00855—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving a step of exchanging information with a remote server
    • G11B20/00862—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving a step of exchanging information with a remote server wherein the remote server can grant the permission to use a content
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
    • G11B20/00855—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving a step of exchanging information with a remote server
    • G11B20/00869—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving a step of exchanging information with a remote server wherein the remote server can deliver the content to a receiving device
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
    • H04L9/0822—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) using key encryption key
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/08—Key distribution or management, e.g. generation, sharing or updating, of cryptographic keys or passwords
    • H04L9/0816—Key establishment, i.e. cryptographic processes or cryptographic protocols whereby a shared secret becomes available to two or more parties, for subsequent use
    • H04L9/0819—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s)
    • H04L9/0825—Key transport or distribution, i.e. key establishment techniques where one party creates or otherwise obtains a secret value, and securely transfers it to the other(s) using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G11B2220/21—Disc-shaped record carriers characterised in that the disc is of read-only, rewritable, or recordable type
    • G11B2220/215—Recordable discs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
    • G11B2220/2537—Optical discs
    • G11B2220/2562—DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L2209/00—Additional information or applications relating to cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
    • H04L2209/60—Digital content management, e.g. content distribution
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L2209/00—Additional information or applications relating to cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00
    • H04L2209/60—Digital content management, e.g. content distribution
    • H04L2209/603—Digital right managament [DRM]

Definitions

  • the present invention relates to a method of recording content, a method of providing a title key, an apparatus for recording content, and a content providing server, which can prevent unauthorized users from recording the title key on a plurality of discs.
  • Content scrambling system is a digital rights management (DRM) scheme used to prevent people from illegally copying and modifying content. Accordingly, a content provider may try to prevent content from being illegally copied and modified while transmitting the content to an authorized user by using DRM.
  • DRM digital rights management
  • the right to use keys for reproducing encrypted content recorded on a recording medium needs to be acquired, and a method of securely transmitting content between a user and the content provider is needed.
  • CSS reproduces video data by using a plurality of keys and decryption processes.
  • the keys used by the CSS include:
  • a disc key that is an encrypted key used to decrypt encrypted title keys, stored in a disc, and uniquely assigned to each disc
  • a title key that is an encrypted key uniquely assigned to each video title set (VTS), used to decrypt encrypted some or all video data included in the VTS, and stored in a header of each title
  • a player key that is a key uniquely assigned to each of DVD reproducing apparatus for consumers and reproduction software for PCs, and used to decrypt disc key.
  • FIG. 1 is a view for explaining a method of reproducing a CSS-encrypted DVD 100.
  • the DVD 100 includes an encrypted disc key, encrypted title keys, and scrambled video data.
  • a reproducing apparatus 110 decrypts the encrypted disc key by using a player key stored therein to obtain a disc key 140.
  • the reproducing apparatus 110 decrypts the encrypted title keys by using the disc key 140 to obtain a title key 160.
  • the reproducing apparatus 110 de-scrambles the scrambled video data by using the title key 160 to obtain and reproduce video data.
  • CSS managed recording is a technology that enables commercial content to be downloaded through a network and recorded on an empty DVD by using the same CSS as a prerecorded commercial DVD title.
  • FIG. 2 is a view for explaining CSS managed recording.
  • a content providing server 210 provides a title key 230 and video data 220, which is CSS encrypted with the title key 230, to a user 240.
  • a user recording apparatus 250 of the user 240 records the encrypted video data 220 on a disc 270 by using the title key 230 and also records a title key 280, which is encrypted with a disc key 290, on the disc 270.
  • the disc key 290 which is encrypted with a player key 260, is already stored in the disc 270.
  • FIG. 3 is a view for explaining encryption and decryption expressions used in the present invention.
  • FIG. 3(a) shows a case where a message is encrypted by using an A key, which may be expressed as E[A key, message].
  • FIG. 3(b) shows a case where a message, which is encrypted with an A key, is decrypted by using the A key, which may be expressed as D[A key, E[A key, message]].
  • FIGS. 4A to 4G are views for explaining the application of conventional CSS managed recording.
  • a content providing server 210 includes a title key 230 and content 220 that is encrypted with the title key 230.
  • a player key 260 is stored in a user recording apparatus 250 of a user, and a user public key CEpub Key 410 and a user private key CEpriv Key 420 form a public key set for the user to securely transmit and decrypt the title key 230.
  • the user public key CEpub Key 410 and the user private key CEpriv Key 420 are a key set generated by public-key cryptography, and the same key set is assigned to devices, that is, recording apparatuses, of the same model.
  • public-key cryptography is a form of cryptography in which a pair of keys, i.e., a public key and a private key are used. Any one of the pair of keys can be used to encrypt data and the other key can be used to decrypt the encrypted data.
  • the public key is widely distributed to all users, the private key is kept secret by a key owner.
  • the user transmits the user public key 410, which is to be used to encrypt the title key 230, to the content providing server 210.
  • the content providing server 210 encrypts the title key 230 by using the user public key 410 received from the user, and transmits a title key 430, which is encrypted with the user public key 410, to the user recording apparatus 250 along with the content 220 that is encrypted with the title key 230.
  • the user recording apparatus 250 decrypts the title key 430, which is encrypted with the user public key 410, by using the user private key 420 to extract the title key 230.
  • the user recording apparatus 250 extracts a disc key 290, which is encrypted with the player key 260, from the recording disc 270, and decrypts the disc key 290, which is encrypted with the player key 260, by using the player key 260 stored in the user recording apparatus 250 to obtain a disc key 440.
  • the user recording apparatus 250 encrypts the title key 230 received from the content providing server 210 by using the disc key 440 to generate a title key 450 that is encrypted with the disc key 440.
  • the user recording apparatus 250 records the CSS encrypted content 220, which is downloaded from the content providing server 210, and the title key 450, which is encrypted with the disc key 440, on the recording disc 270.
  • FIGS. 5 A to 5E are views for explaining problems caused during the application of the conventional CSS managed recording of FIGS. 4A to 4G.
  • recording apparatuses 250 of the same model have the same public key 410 and the same private key 420. Both an authorized user A and an unauthorized user B can download CSS encrypted content from a content providing server 210.
  • the authorized user A trying to buy a title key 430 for the purpose of recording the downloaded content on a recording disc transmits a user public key 410 of the user recording apparatus 250 for encrypting the title key 430 to the content providing server 210.
  • the content providing server 210 encrypts the title key 430 by using the received public key 410 of the user recording apparatus 250.
  • the unauthorized user B may intercept the title key 430.
  • the unauthorized user B intercepting the title key 430, which is encrypted with the public key 410 of the user recording apparatus 250, has the same key set as that of the authorized user A because the user recording apparatuses 250 of the authorized user A and the unauthorized user B are of the same model. Accordingly, the unauthorized user B can decrypt the title key 430, which is encrypted with the public key 410, by using a private key 420 of the user recording apparatus 250 and extract a title key 230. Also, the unauthorized user B can encrypt the extracted title key 230 by using a disc key 440 and generate a title key 450, which is encrypted with the disc key 440. As a result, the unauthorized user B can record the content on a recording disc without buying the title key 430. Disclosure of Invention Technical Problem
  • the unauthorized user B can extract a disc key 530 from a new disc 510 and encrypt the title key 230 by using the disc key 530, the unauthorized user B can record the content on the new disc 510 as well. That is, since the unauthorized user B stores the decrypted title key 230, the unauthorized user B can extract a disc key from a new recording disc and encrypt the title key 230 by using the extracted disc key, and thus the unauthorized user B can record the content on a plurality of discs.
  • the present invention provides a method of recording content, a method of providing a title key, an apparatus for recording content, and a content providing server, which can prevent unauthorized users from recording the title key on a plurality of discs.
  • FIG. 1 is a view for explaining a method of reproducing a content scrambling system
  • FIG. 2 is a view for explaining CSS managed recording
  • FIG. 3 is a view for explaining encryption and decryption expressions used in the present invention
  • FIGS. 4A to 4G are views for explaining the application of conventional CSS managed recording
  • FIGS. 5 A to 5E are views for explaining problems caused during the application of the conventional CSS managed recording of FIGS. 4A to 4G
  • FIGS. 6 A to 6F are views is a view for explaining a method of transmitting and receiving data between a content providing server and a user recording apparatus according to an embodiment of the present invention
  • FIG. 7 is a view for explaining advantages of the method of FIGS. 6A to 6F when an unauthorized user intercepts a title key
  • FIG. 4A to 4G are views for explaining the application of conventional CSS managed recording
  • FIGS. 5 A to 5E are views for explaining problems caused during the application of the conventional CSS managed recording of FIGS. 4A to 4G
  • FIGS. 6 A to 6F are views is a view for explaining a method of transmitting and receiving data between a content providing server and a user recording apparatus according to
  • FIG. 8 is a block diagram of a content providing server and a user recording apparatus according to an embodiment of the present invention.
  • FIG. 9 is a flowchart illustrating a method of recording encrypted content in a user recording apparatus according to an embodiment of the present invention.
  • FIG. 10 is a flowchart illustrating a method of providing a title key from a content providing server to a user recording apparatus according to an embodiment of the present invention.
  • a method of recording content downloaded from a network comprising: receiving a title key, which is encrypted with a disc key of a disc on which content is to be recorded in a recording apparatus, from a server; and recording the received title key and the content on the disc.
  • the receiving of the title key from the server may comprise transmitting the disc key to the server.
  • the transmitting of the disc key to the server may comprise: receiving a public key of the server from the server; encrypting the disc key by using the public key of the server; and transmitting the disc key, which is encrypted with the public key of the server, to the server.
  • a method of providing a title key to a recording apparatus for recording content downloaded from a network comprising: receiving a disc key of a disc on which content is to be recorded from the recording apparatus; encrypting the title key by using the received disc key; and transmitting the title key, which is encrypted with the disc key, to the recording apparatus.
  • the receiving of the disc key from the recording apparatus may comprise: transmitting a public key of the server to the recording apparatus; and receiving the disc key, which is encrypted with the public key of the server, from the recording apparatus.
  • the encrypting of the title key by using the received disc key may comprise: decrypting the disc key, which is encrypted with the public key of the server, by using a private key of the server to obtain the disc key; and encrypting the title key, which has been used to encrypt the content, by using the disc key.
  • an apparatus for recording content downloaded from a network comprising: a recording unit recording downloaded content on a disc; and a control unit receiving the content and a title key, which is encrypted with a disc key of a disc on which content is to be recorded, from a content providing server, and controlling the recording unit to record the title key, which is encrypted with the received disc key, and the content on the disc.
  • a content providing server for providing a title key to a recording apparatus for recording content downloaded from a network
  • the content providing server comprising: an encryption/ decryption unit encrypting/decrypting data; and a control unit receiving a disc key of a disc on which the content is to be recorded from the recording apparatus, controlling the encryption/decryption unit to encrypt the title key by using the received disc key, and transmitting the title key, which is encrypted with the disc key, and the content to the recording apparatus.
  • the present invention uses a public key and a private key generated by a content providing server to receive a title key, which is encrypted with a disc key obtained by an authorized user, from the content providing server, and securely transmit the disc key, which only the authorized user owns, to the content providing server.
  • FIGS. 6A to 6F are views for explaining a method of transmitting and receiving data between a content providing server 610 and a user recording apparatus 620 according to an embodiment of the present invention.
  • the content providing server 610 includes a public key 611, a private key 612, a title key 614, and content 613 that is encrypted with the title key 614.
  • the user recording apparatus 620 includes a player key 621 stored therein, and a disc 630 on which the content 613 is to be recorded and in which a disc key 631, which is encrypted with the player key 621, is stored.
  • the user recording apparatus 620 receives the content 613, which is content scrambling system (CSS) encrypted with the title key 614, and the public key 611 from the content providing server 610.
  • the encrypted content 613 and the public key 611 of the content providing server 610 may be transmitted together or may be separately transmitted to the user recording apparatus 620.
  • the user recording apparatus 620 extracts the disc key 631, which is encrypted with the player key 621, from the disc 630, and decrypts the disc key 631, which is encrypted with the player key 621, by using the player key 621 to obtain the disc key 631.
  • the user recording apparatus 620 encrypts the disc key 631 by using the public key 611 received from the content providing server 610, and transmits the encrypted disc key 631 to the content providing server 610.
  • the content providing server 610 decrypts the disc key 631, which is encrypted with the public key 611 of the content providing server 610, by using the private key 612 to obtain the disc key 631. Then, the content providing server 610 encrypts the title key 614, which has been used to encrypt the content 613, by using the disc key 631.
  • the content providing server 610 transmits the title key 614, which is encrypted with the disc key 631, to the user recording apparatus 620.
  • the user recording apparatus 620 records the downloaded CSS encrypted content 613 and the title key 614, which is encrypted with the disc key 631, on the disc 630.
  • the above-described method of FIGS. 6A to 6F can prevent an unauthorized user B from recording the content 613 even when the unauthorized user B intercepts the title key 614.
  • FIG. 7 is a view for explaining advantages of the method of FIGS. 6A to 6F when the unauthorized user B intercepts the title key 614.
  • FIG. 8 is a block diagram of a content providing server 810 and a user recording apparatus 830 according to an embodiment of the present invention.
  • the content providing server 810 is a computer that provides encrypted content and a title key, which has been used to encrypt the content, to the user recording apparatus 830.
  • the content providing server 810 may be any type of computer so long as it can provide encrypted content and a title key used to encrypt the content.
  • the content providing server 810 may include two or more computers so that a computer provides encrypted computer and another computer provides a title key used to encrypt the content.
  • the user recording apparatus 830 which records encrypted content and a title key used to encrypt the content, on a recording disc 840, may be any type of recording apparatus so long as it can record encrypted content and a title key used to encrypt the content, on the recording disc 840.
  • the content providing server 810 and the user recording apparatus 830 are connected to each other through a communication network 820. That is, the content providing server 810 and the user recording apparatus 830 transmit and receive other keys that are transmitted and received to securely transmit encrypted content and a title key used to encrypt the content through the communication network 820.
  • the content providing server 810 includes a communication unit 811, an encryption/ decryption unit 812, and a control unit 813.
  • the communication unit 811 transmits encrypted content, a title key used to encrypt the content, and other keys to the user recording apparatus 830 through the communication network 820, and receives predetermined keys sent from the user recording apparatus 830.
  • the communication unit 811 transmits encrypted content 613, a public key 611 of the content providing server 810, and a title key, which is encrypted with a disc key, to the user recording apparatus 830, and receives the disc key, which is encrypted with the public key 611 of the content providing server 810, from the user recording apparatus 830.
  • the encryption/decryption unit 812 encrypts or decrypts content and predetermined keys.
  • the encryption/decryption unit 812 receives the disc key, which is encrypted with the public key 611 of the content providing server 810, from the user recording apparatus 830, decrypts the disc key, which is encrypted with the public key 611 of the content providing server 810, by using a private key of the content providing server 810 to obtain the disc key, and encrypts the title key by using the disc key.
  • the control unit 813 controls to transmit the encrypted content 613 and a title key to the user recording apparatus 830, and also controls the communication unit 811 and the encryption/decryption unit 812.
  • the content providing server 810 may further include a memory or a hard disc as a storing unit in which the encrypted content 613, the title key, the public key 611, and the private key are stored.
  • the user recording apparatus 830 includes a communication unit 821, an encryption/ decryption unit 822, a recording unit 823, and a control unit 824.
  • the communication unit 821 receives the encrypted content 613, the title key used to encrypt the content 613, and other keys from the user recording apparatus 830 through the communication network 820, and transmits predetermined keys to the content providing server 810.
  • the communication unit 821 receives the public key 611, the encrypted content 613, and the title key, which is encrypted with the disc key, from the content providing server 810, and transmits the disc key, which is encrypted with the public key 611, to the content providing server 810.
  • the encryption/decryption unit 822 encrypts or decrypts predetermined keys. That is, the encryption/decryption unit 822 reads out the encrypted disc key, which is stored in the recording disc 840, and decrypts the encrypted disc key by using a player key of the user recording apparatus 830 to obtain the disc key. The encryption/decryption unit 822 encrypts the obtained disc key by using the public key 611 of the content providing server 810.
  • the recording unit 823 records the encrypted content 613 and the title key, which is encrypted with the disc key, received from the content providing server 810 on the recording disc 840.
  • control unit 824 controls the recording unit 823 to receive the encrypted content
  • the user recording apparatus 830 has the player key stored therein.
  • FIG. 9 is a flowchart illustrating a method of recording encrypted content in a user recording apparatus according to an embodiment of the present invention.
  • the user recording apparatus receives a title key, which is encrypted with a disc key of a disc on which the content is to be recorded, from a content providing server.
  • the user recording apparatus may transmit the disc key of the disc on which the content is to be recorded to the content providing server.
  • the disc key transmitted to the content providing server may be encrypted by using a public key of the content providing server.
  • FIG. 10 is a flowchart illustrating a method of providing a title key from a content providing server to a user recording apparatus according to an embodiment of the present invention.
  • a disc key of a disc on which content is to be recorded is received from the user recording apparatus.
  • the disc key received from the user recording apparatus may be encrypted by using a public key of the content providing server.
  • the content providing server may transmit the public key to the user recording apparatus.
  • the title key is encrypted by using the received disc key. If the received disc key has already been encrypted with the public key of the content providing server, the content providing server decrypts the disc key, that is encrypted with the public key of the content providing server, by using a private key of the content providing server to obtain the disc key, and encrypts the title key, which is used to encrypt the content, by using the obtained disc key.
  • the title key which is encrypted with the disc key, is transmitted to the user recording apparatus.
  • the present invention may be embodied as computer-readable codes on a computer- readable recording medium.
  • the computer-readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer-readable recording medium include read-only memories (ROMs), random-access memories (RAMs), CD-ROMs, magnetic tapes, floppy discs, and optical data storage devices.
  • ROMs read-only memories
  • RAMs random-access memories

Abstract

Provided are a method of recording content, a method of providing a title key, an apparatus for recording content, and a content providing server, which can prevent unauthorized users from recording the title key on a plurality of discs. The method of recording content downloaded from a network includes: receiving a title key, which is encrypted with a disc key of a disc on which content is to be recorded in a recording apparatus, from a server; and recording the received title key and the content on the disc.

Description

Description
METHOD OF RECORDING CONTENT ON DISC, METHOD OF PROVIDING TITLE KEY, APPARATUS FOR RECORDING
CONTENT ON DISC, AND CONTENT PROVIDING SERVER
Technical Field
[1] The present invention relates to a method of recording content, a method of providing a title key, an apparatus for recording content, and a content providing server, which can prevent unauthorized users from recording the title key on a plurality of discs. Background Art
[2] The recent rapid development of network infrastructure enables moving pictures to be easily traded through the Internet. Some service providers plan to provide services that allow a user or a rental shop to download video content through the Internet to a digital versatile disc (DVD). If a charge for this service is lower than a DVD purchase price, consumers will be able to enjoy high quality video content at home while saving money and time.
[3] That is, content providers may use a network in order to more easily sell content, and users may be able to easily download various movie content through the network.
[4] As such, since there is a high possibility that the content downloaded through the network will be illegally copied and modified, there is an increasing need for protection against illegal copying.
[5] Content scrambling system (CSS) is a digital rights management (DRM) scheme used to prevent people from illegally copying and modifying content. Accordingly, a content provider may try to prevent content from being illegally copied and modified while transmitting the content to an authorized user by using DRM. In order to use DRM, the right to use keys for reproducing encrypted content recorded on a recording medium needs to be acquired, and a method of securely transmitting content between a user and the content provider is needed.
[6] In particular, since a DVD can be directly played on a personal computer (PC) unlike in the case of other media, the possibility that the DVD may be copied to other hard discs is very high. CSS, which is a DRAM scheme, has been suggested to prevent such illegal copying.
[7] CSS reproduces video data by using a plurality of keys and decryption processes.
The keys used by the CSS include:
[8] a disc key that is an encrypted key used to decrypt encrypted title keys, stored in a disc, and uniquely assigned to each disc; [9] a title key that is an encrypted key uniquely assigned to each video title set (VTS), used to decrypt encrypted some or all video data included in the VTS, and stored in a header of each title; and
[10] a player key that is a key uniquely assigned to each of DVD reproducing apparatus for consumers and reproduction software for PCs, and used to decrypt disc key.
[11] FIG. 1 is a view for explaining a method of reproducing a CSS-encrypted DVD 100.
[12] Referring to FIG. 1, the DVD 100 includes an encrypted disc key, encrypted title keys, and scrambled video data. In operation 130, a reproducing apparatus 110 decrypts the encrypted disc key by using a player key stored therein to obtain a disc key 140. In operation 150, the reproducing apparatus 110 decrypts the encrypted title keys by using the disc key 140 to obtain a title key 160. In operation 170, the reproducing apparatus 110 de-scrambles the scrambled video data by using the title key 160 to obtain and reproduce video data.
[13] CSS managed recording is a technology that enables commercial content to be downloaded through a network and recorded on an empty DVD by using the same CSS as a prerecorded commercial DVD title.
[14] FIG. 2 is a view for explaining CSS managed recording.
[15] Referring to FIG. 2, a content providing server 210 provides a title key 230 and video data 220, which is CSS encrypted with the title key 230, to a user 240. A user recording apparatus 250 of the user 240 records the encrypted video data 220 on a disc 270 by using the title key 230 and also records a title key 280, which is encrypted with a disc key 290, on the disc 270. The disc key 290, which is encrypted with a player key 260, is already stored in the disc 270.
[16] FIG. 3 is a view for explaining encryption and decryption expressions used in the present invention.
[17] FIG. 3(a) shows a case where a message is encrypted by using an A key, which may be expressed as E[A key, message]. FIG. 3(b) shows a case where a message, which is encrypted with an A key, is decrypted by using the A key, which may be expressed as D[A key, E[A key, message]].
[18] FIGS. 4A to 4G are views for explaining the application of conventional CSS managed recording.
[19] Referring to FIG. 4A, a content providing server 210 includes a title key 230 and content 220 that is encrypted with the title key 230. A player key 260 is stored in a user recording apparatus 250 of a user, and a user public key CEpub Key 410 and a user private key CEpriv Key 420 form a public key set for the user to securely transmit and decrypt the title key 230. The user public key CEpub Key 410 and the user private key CEpriv Key 420 are a key set generated by public-key cryptography, and the same key set is assigned to devices, that is, recording apparatuses, of the same model. In detail, public-key cryptography is a form of cryptography in which a pair of keys, i.e., a public key and a private key are used. Any one of the pair of keys can be used to encrypt data and the other key can be used to decrypt the encrypted data. In general, while the public key is widely distributed to all users, the private key is kept secret by a key owner.
[20] Referring to FIG. 4B, in order to securely obtain the title key 230 required to reproduce the encrypted content 220 from the content providing server 210, the user transmits the user public key 410, which is to be used to encrypt the title key 230, to the content providing server 210.
[21] Referring to FIG. 4C, the content providing server 210 encrypts the title key 230 by using the user public key 410 received from the user, and transmits a title key 430, which is encrypted with the user public key 410, to the user recording apparatus 250 along with the content 220 that is encrypted with the title key 230.
[22] Referring to FIG. 4D, the user recording apparatus 250 decrypts the title key 430, which is encrypted with the user public key 410, by using the user private key 420 to extract the title key 230.
[23] Referring to FIG. 4E, the user recording apparatus 250 extracts a disc key 290, which is encrypted with the player key 260, from the recording disc 270, and decrypts the disc key 290, which is encrypted with the player key 260, by using the player key 260 stored in the user recording apparatus 250 to obtain a disc key 440.
[24] Referring to FIG. 4F, the user recording apparatus 250 encrypts the title key 230 received from the content providing server 210 by using the disc key 440 to generate a title key 450 that is encrypted with the disc key 440.
[25] Referring to FIG. 4G, the user recording apparatus 250 records the CSS encrypted content 220, which is downloaded from the content providing server 210, and the title key 450, which is encrypted with the disc key 440, on the recording disc 270.
[26] FIGS. 5 A to 5E are views for explaining problems caused during the application of the conventional CSS managed recording of FIGS. 4A to 4G.
[27] Referring to FIG. 5A, recording apparatuses 250 of the same model have the same public key 410 and the same private key 420. Both an authorized user A and an unauthorized user B can download CSS encrypted content from a content providing server 210.
[28] Referring to FIG. 5B, the authorized user A trying to buy a title key 430 for the purpose of recording the downloaded content on a recording disc transmits a user public key 410 of the user recording apparatus 250 for encrypting the title key 430 to the content providing server 210. The content providing server 210 encrypts the title key 430 by using the received public key 410 of the user recording apparatus 250.
[29] Referring to FIG. 5C, while the content providing server 210 transmits the title key 430, which is encrypted with the public key 410 of the recording apparatus 250, to the user recording apparatus 250 of the authorized user A, the unauthorized user B may intercept the title key 430.
[30] Referring to FIG. 5D, the unauthorized user B intercepting the title key 430, which is encrypted with the public key 410 of the user recording apparatus 250, has the same key set as that of the authorized user A because the user recording apparatuses 250 of the authorized user A and the unauthorized user B are of the same model. Accordingly, the unauthorized user B can decrypt the title key 430, which is encrypted with the public key 410, by using a private key 420 of the user recording apparatus 250 and extract a title key 230. Also, the unauthorized user B can encrypt the extracted title key 230 by using a disc key 440 and generate a title key 450, which is encrypted with the disc key 440. As a result, the unauthorized user B can record the content on a recording disc without buying the title key 430. Disclosure of Invention Technical Problem
[31] Referring to FIG. 5E, since the unauthorized user B can extract a disc key 530 from a new disc 510 and encrypt the title key 230 by using the disc key 530, the unauthorized user B can record the content on the new disc 510 as well. That is, since the unauthorized user B stores the decrypted title key 230, the unauthorized user B can extract a disc key from a new recording disc and encrypt the title key 230 by using the extracted disc key, and thus the unauthorized user B can record the content on a plurality of discs. Technical Solution
[32] The present invention provides a method of recording content, a method of providing a title key, an apparatus for recording content, and a content providing server, which can prevent unauthorized users from recording the title key on a plurality of discs. Advantageous Effects
[33] According to the present invention, unauthorized users cannot record a title key on a plurality of discs. Description of Drawings
[34] The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
[35] FIG. 1 is a view for explaining a method of reproducing a content scrambling system
(CSS)-encrypted digital versatile disc (DVD);
[36] FIG. 2 is a view for explaining CSS managed recording;
[37] FIG. 3 is a view for explaining encryption and decryption expressions used in the present invention; [38] FIGS. 4A to 4G are views for explaining the application of conventional CSS managed recording; [39] FIGS. 5 A to 5E are views for explaining problems caused during the application of the conventional CSS managed recording of FIGS. 4A to 4G; [40] FIGS. 6 A to 6F are views is a view for explaining a method of transmitting and receiving data between a content providing server and a user recording apparatus according to an embodiment of the present invention; [41] FIG. 7 is a view for explaining advantages of the method of FIGS. 6A to 6F when an unauthorized user intercepts a title key; [42] FIG. 8 is a block diagram of a content providing server and a user recording apparatus according to an embodiment of the present invention; [43] FIG. 9 is a flowchart illustrating a method of recording encrypted content in a user recording apparatus according to an embodiment of the present invention; and [44] FIG. 10 is a flowchart illustrating a method of providing a title key from a content providing server to a user recording apparatus according to an embodiment of the present invention.
Best Mode [45] According to an aspect of the present invention, there is provided a method of recording content downloaded from a network, the method comprising: receiving a title key, which is encrypted with a disc key of a disc on which content is to be recorded in a recording apparatus, from a server; and recording the received title key and the content on the disc. [46] The receiving of the title key from the server may comprise transmitting the disc key to the server. [47] The transmitting of the disc key to the server may comprise: receiving a public key of the server from the server; encrypting the disc key by using the public key of the server; and transmitting the disc key, which is encrypted with the public key of the server, to the server. [48] According to another aspect of the present invention, there is provided a method of providing a title key to a recording apparatus for recording content downloaded from a network, the method comprising: receiving a disc key of a disc on which content is to be recorded from the recording apparatus; encrypting the title key by using the received disc key; and transmitting the title key, which is encrypted with the disc key, to the recording apparatus. [49] The receiving of the disc key from the recording apparatus may comprise: transmitting a public key of the server to the recording apparatus; and receiving the disc key, which is encrypted with the public key of the server, from the recording apparatus.
[50] The encrypting of the title key by using the received disc key may comprise: decrypting the disc key, which is encrypted with the public key of the server, by using a private key of the server to obtain the disc key; and encrypting the title key, which has been used to encrypt the content, by using the disc key.
[51] According to another aspect of the present invention, there is provided an apparatus for recording content downloaded from a network, the apparatus comprising: a recording unit recording downloaded content on a disc; and a control unit receiving the content and a title key, which is encrypted with a disc key of a disc on which content is to be recorded, from a content providing server, and controlling the recording unit to record the title key, which is encrypted with the received disc key, and the content on the disc.
[52] According to another aspect of the present invention, there is provided a content providing server for providing a title key to a recording apparatus for recording content downloaded from a network, the content providing server comprising: an encryption/ decryption unit encrypting/decrypting data; and a control unit receiving a disc key of a disc on which the content is to be recorded from the recording apparatus, controlling the encryption/decryption unit to encrypt the title key by using the received disc key, and transmitting the title key, which is encrypted with the disc key, and the content to the recording apparatus. Mode for Invention
[53] The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.
[54] For the purpose of preventing an unauthorized user who intercepts an encrypted title key from decrypting the encrypted title key, the present invention uses a public key and a private key generated by a content providing server to receive a title key, which is encrypted with a disc key obtained by an authorized user, from the content providing server, and securely transmit the disc key, which only the authorized user owns, to the content providing server.
[55] FIGS. 6A to 6F are views for explaining a method of transmitting and receiving data between a content providing server 610 and a user recording apparatus 620 according to an embodiment of the present invention.
[56] Referring to FIG. 6A, the content providing server 610 includes a public key 611, a private key 612, a title key 614, and content 613 that is encrypted with the title key 614. The user recording apparatus 620 includes a player key 621 stored therein, and a disc 630 on which the content 613 is to be recorded and in which a disc key 631, which is encrypted with the player key 621, is stored.
[57] The user recording apparatus 620 receives the content 613, which is content scrambling system (CSS) encrypted with the title key 614, and the public key 611 from the content providing server 610. The encrypted content 613 and the public key 611 of the content providing server 610 may be transmitted together or may be separately transmitted to the user recording apparatus 620.
[58] Referring to FIG. 6B, the user recording apparatus 620 extracts the disc key 631, which is encrypted with the player key 621, from the disc 630, and decrypts the disc key 631, which is encrypted with the player key 621, by using the player key 621 to obtain the disc key 631.
[59] Referring to FIG. 6C, the user recording apparatus 620 encrypts the disc key 631 by using the public key 611 received from the content providing server 610, and transmits the encrypted disc key 631 to the content providing server 610.
[60] Referring to FIG. 6D, the content providing server 610 decrypts the disc key 631, which is encrypted with the public key 611 of the content providing server 610, by using the private key 612 to obtain the disc key 631. Then, the content providing server 610 encrypts the title key 614, which has been used to encrypt the content 613, by using the disc key 631.
[61] Referring to FIG. 6E, the content providing server 610 transmits the title key 614, which is encrypted with the disc key 631, to the user recording apparatus 620.
[62] Referring to FIG. 6F, the user recording apparatus 620 records the downloaded CSS encrypted content 613 and the title key 614, which is encrypted with the disc key 631, on the disc 630.
[63] Accordingly, the above-described method of FIGS. 6A to 6F can prevent an unauthorized user B from recording the content 613 even when the unauthorized user B intercepts the title key 614.
[64] FIG. 7 is a view for explaining advantages of the method of FIGS. 6A to 6F when the unauthorized user B intercepts the title key 614.
[65] Referring to FIG. 7, even when the unauthorized user B intercepts the title key 614, which is encrypted with the disc key 631, while the title key 614 is transmitted from the content providing server 610 to the user recording apparatus 620, since the unauthorized user B does not have the disc key 631 used to decrypt the title key 614 that is encrypted with the disc key 631, the unauthorized user B cannot decrypt the title key 614. That is, since a disc key is uniquely assigned to each disc, the unauthorized user B cannot decrypt the encrypted title key 614 by using a disc key of a disc that the unauthorized user B possesses.
[66] Even though the unauthorized user B intercepts the disc key 631, which is encrypted with the public key 611 of the content providing server 610, while the disc key 631 is transmitted as shown in FIG. 6C in order to obtain the disc key 631 of an authorized user A, it is also impossible for the unauthorized user B to decrypt the disc key 631 that is encrypted with the public key 611 of the content providing server 610. This is because the unauthorized user B should decrypt the disc key 631, which is encrypted with the public key 611 of the content providing server 610, by using the private key 612 of the content providing server 610, but the unauthorized user B cannot have the private key 612 of the content providing server 610.
[67] FIG. 8 is a block diagram of a content providing server 810 and a user recording apparatus 830 according to an embodiment of the present invention.
[68] Referring to FIG. 8, the content providing server 810 is a computer that provides encrypted content and a title key, which has been used to encrypt the content, to the user recording apparatus 830. The content providing server 810 may be any type of computer so long as it can provide encrypted content and a title key used to encrypt the content. The content providing server 810 may include two or more computers so that a computer provides encrypted computer and another computer provides a title key used to encrypt the content.
[69] The user recording apparatus 830, which records encrypted content and a title key used to encrypt the content, on a recording disc 840, may be any type of recording apparatus so long as it can record encrypted content and a title key used to encrypt the content, on the recording disc 840.
[70] The content providing server 810 and the user recording apparatus 830 are connected to each other through a communication network 820. That is, the content providing server 810 and the user recording apparatus 830 transmit and receive other keys that are transmitted and received to securely transmit encrypted content and a title key used to encrypt the content through the communication network 820.
[71] The content providing server 810 includes a communication unit 811, an encryption/ decryption unit 812, and a control unit 813.
[72] The communication unit 811 transmits encrypted content, a title key used to encrypt the content, and other keys to the user recording apparatus 830 through the communication network 820, and receives predetermined keys sent from the user recording apparatus 830. In detail, the communication unit 811 transmits encrypted content 613, a public key 611 of the content providing server 810, and a title key, which is encrypted with a disc key, to the user recording apparatus 830, and receives the disc key, which is encrypted with the public key 611 of the content providing server 810, from the user recording apparatus 830.
[73] The encryption/decryption unit 812 encrypts or decrypts content and predetermined keys. The encryption/decryption unit 812 receives the disc key, which is encrypted with the public key 611 of the content providing server 810, from the user recording apparatus 830, decrypts the disc key, which is encrypted with the public key 611 of the content providing server 810, by using a private key of the content providing server 810 to obtain the disc key, and encrypts the title key by using the disc key.
[74] The control unit 813 controls to transmit the encrypted content 613 and a title key to the user recording apparatus 830, and also controls the communication unit 811 and the encryption/decryption unit 812.
[75] Although not shown, the content providing server 810 may further include a memory or a hard disc as a storing unit in which the encrypted content 613, the title key, the public key 611, and the private key are stored.
[76] The user recording apparatus 830 includes a communication unit 821, an encryption/ decryption unit 822, a recording unit 823, and a control unit 824.
[77] The communication unit 821 receives the encrypted content 613, the title key used to encrypt the content 613, and other keys from the user recording apparatus 830 through the communication network 820, and transmits predetermined keys to the content providing server 810. In detail, the communication unit 821 receives the public key 611, the encrypted content 613, and the title key, which is encrypted with the disc key, from the content providing server 810, and transmits the disc key, which is encrypted with the public key 611, to the content providing server 810.
[78] The encryption/decryption unit 822 encrypts or decrypts predetermined keys. That is, the encryption/decryption unit 822 reads out the encrypted disc key, which is stored in the recording disc 840, and decrypts the encrypted disc key by using a player key of the user recording apparatus 830 to obtain the disc key. The encryption/decryption unit 822 encrypts the obtained disc key by using the public key 611 of the content providing server 810.
[79] The recording unit 823 records the encrypted content 613 and the title key, which is encrypted with the disc key, received from the content providing server 810 on the recording disc 840.
[80] The control unit 824 controls the recording unit 823 to receive the encrypted content
613 and the title key from the content providing server 810 and to record the encrypted content 613 and the title key on the recording disc 840, and also controls the communication unit 821, the encryption/decryption unit 822, and the recording unit 823. The user recording apparatus 830 has the player key stored therein.
[81] FIG. 9 is a flowchart illustrating a method of recording encrypted content in a user recording apparatus according to an embodiment of the present invention.
[82] Referring to FIG. 9, in operation 910, the user recording apparatus receives a title key, which is encrypted with a disc key of a disc on which the content is to be recorded, from a content providing server. In order to receive the title key that is encrypted with the disc key from the content providing server, the user recording apparatus may transmit the disc key of the disc on which the content is to be recorded to the content providing server. The disc key transmitted to the content providing server may be encrypted by using a public key of the content providing server.
[83] In operation 920, the title key, which is encrypted with the received disc key, and the content are recorded on the disc.
[84] FIG. 10 is a flowchart illustrating a method of providing a title key from a content providing server to a user recording apparatus according to an embodiment of the present invention.
[85] Referring to FIG. 10, in operation 1010, a disc key of a disc on which content is to be recorded is received from the user recording apparatus. For stable transmission and reception, the disc key received from the user recording apparatus may be encrypted by using a public key of the content providing server. To this end, the content providing server may transmit the public key to the user recording apparatus.
[86] In operation 1020, the title key is encrypted by using the received disc key. If the received disc key has already been encrypted with the public key of the content providing server, the content providing server decrypts the disc key, that is encrypted with the public key of the content providing server, by using a private key of the content providing server to obtain the disc key, and encrypts the title key, which is used to encrypt the content, by using the obtained disc key.
[87] In operation 1030, the title key, which is encrypted with the disc key, is transmitted to the user recording apparatus.
[88] As described above, according to the present invention, unauthorized users cannot record a title key on a plurality of discs.
[89] The present invention may be embodied as computer-readable codes on a computer- readable recording medium. The computer-readable recording medium is any data storage device that can store data which can be thereafter read by a computer system. Examples of the computer-readable recording medium include read-only memories (ROMs), random-access memories (RAMs), CD-ROMs, magnetic tapes, floppy discs, and optical data storage devices. The computer-readable recording medium can be dis- persively installed in a computer system connected to a network, and stored and executed as a computer-readable code in a distributed computing environment. Functional programs, codes, and code segments for embodying the present invention may be easily deducted by programmers in the art which the present invention belongs to.
[90] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. The preferred embodiments should be considered in a descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

Claims

Claims
[1] L A method of recording content downloaded from a network, the method comprising: receiving a title key, which is encrypted with a disc key of a disc on which content is to be recorded in a recording apparatus, from a server; and recording the received title key and the content on the disc.
[2] 2. The method of claim 1, wherein the receiving of the title key from the server comprises transmitting the disc key to the server.
[3] 3. The method of claim 2, wherein the transmitting of the disc key to the server comprises: receiving a public key of the server from the server; encrypting the disc key by using the public key of the server; and transmitting the disc key, which is encrypted with the public key of the server, to the server.
[4] 4. A method of providing a title key to a recording apparatus for recording content downloaded from a network, the method comprising: receiving a disc key of a disc on which content is to be recorded from the recording apparatus; encrypting the title key by using the received disc key; and transmitting the title key, which is encrypted with the disc key, to the recording apparatus.
[5] 5. The method of claim 4, wherein the receiving of the disc key from the recording apparatus comprises: transmitting a public key of the server to the recording apparatus; and receiving the disc key, which is encrypted with the public key of the server, from the recording apparatus.
[6] 6. The method of claim 4, wherein the encrypting of the title key by using the received disc key comprises: decrypting the disc key, which is encrypted with the public key of the server, by using a private key of the server to obtain the disc key; and encrypting the title key, which has been used to encrypt the content, by using the disc key.
[7] 7. An apparatus for recording content downloaded from a network, the apparatus comprising: a recording unit recording downloaded content on a disc; and a control unit receiving the content and a title key, which is encrypted with a disc key of a disc on which content is to be recorded, from a content providing server, and controlling the recording unit to record the title key, which is encrypted with the received disc key, and the content on the disc.
[8] 8. The apparatus of claim 7, wherein the control unit transmits the disc key to the server in order to receive the title key, which is encrypted with the disc key, from the server.
[9] 9. The apparatus of claim 8, further comprising an encryption/decryption unit encrypting/decrypting data, wherein, in order to transmit the disc key to the server, the control unit controls the encryption/decryption unit to encrypt the disc key by using the public key of the server received from the server, and transmits the disc key, which is encrypted with the public key of the server, to the server.
[10] 10. A content providing server for providing a title key to a recording apparatus for recording content downloaded from a network, the content providing server comprising: an encryption/decryption unit encrypting/decrypting data; and a control unit receiving a disc key of a disc on which the content is to be recorded from the recording apparatus, controlling the encryption/decryption unit to encrypt the title key by using the received disc key, and transmitting the title key, which is encrypted with the disc key, and the content to the recording apparatus.
[11] 11. The content providing server of claim 10, wherein, in order to receive the disc key from the recording apparatus, the control unit transmits a public key of the server to the recording apparatus and receives the disc key, which is encrypted with the public key of the server, from the recording apparatus.
[12] 12. The content providing server of claim 10, wherein the control unit controls the encryption/decryption unit to decrypt the disc key, which is encrypted with the public key of the server, by using a private key of the server to obtain the disc key, and to encrypt the title key, which has been used to encrypt the content, by using the disc key.
EP08793541.7A 2008-01-09 2008-08-28 Method of recording content on disc, method of providing title key, apparatus for recording content on disc, and content providing server Withdrawn EP2227807A4 (en)

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